1. Field of the Invention
The present invention relates to a tab for temporarily fixing a paper web end portion of a paper roll for use with, for example, a rotary press, in order to prevent unwinding of the paper roll.
2. Description of the Related Art
In, for example, a rotary press, a paper web is fed downstream from a paper roll loaded in a web feeder. When a paper web end of the paper roll is approached, a paper web end portion of a new paper roll is affixed to the currently fed paper web, so that the feed of paper web is not interrupted. In order to achieve this affixing, the paper web end portion of the new paper roll is provided with a special device.
Specifically, as shown in FIG. 7, after a paper web end of a paper roll 52 is cut straight or into a chevron shape, an end portion 50 of paper web of the paper roll 52 is affixed to the surface of the paper roll 52 by means of tabs t in order to prevent unwinding of the paper roll 52. Further, a pressure-sensitive double-sided adhesive tape 51 is affixed to the end portion 50 along its end edge.
Conventional tabs used to temporarily fix the end portion of a paper roll as described above are disclosed in, for example, Japanese Utility Model Application Laid-Open (kokai) Nos. 4-117854 and 5-12440 and Japanese Patent Application Laid-Open (kokai) No. 10-114452.
FIGS. 8A and 8B show a tab ta disclosed in Japanese Utility Model Application Laid-Open (kokai) No. 4-117854 xe2x80x9cTab for Fixing Paper Web End Portion of Paper Roll.xe2x80x9d In this tab ta, a nonadhesive portion 66 is formed at a central portion of a base sheet 53, and adhesive layers 54 and 55 are provided between the nonadhesive portion 66 and the upper edge of the base sheet 53 and between the nonadhesive portion 66 and the lower edge of the base sheet 53, respectively. Further, perforations 56 are formed in the nonadhesive portion 66 such that the perforations extend at intervals of, for example, about 1 mm between the side edges of the nonadhesive portion 66.
The adhesive layers 54 and 55 of a plurality of tabs ta are affixed to the paper roll 52 such that the perforations 56 are aligned with the end edge of the end portion 50 of the paper roll 52, thereby temporarily fixing the end portion 50 on the paper roll 52. When the paper web of a new paper roll 52 is to be joined to the paper web currently being fed (hereinafter called the xe2x80x9ccurrently fed paper webxe2x80x9d), the pressure-sensitive double-sided adhesive tape 51 adhering to the end portion 50 of the new paper roll 52 is affixed to the currently fed paper web. As a result, each of the base sheets 53 is torn apart, along the perforations 56, into upper and lower pieces, so that the end portion 50 of the new paper roll 52 is released from temporary fixation.
FIGS. 9A and 9B show a tab tb disclosed in Japanese Patent Application Laid-Open (kokai) No. 10-114452 xe2x80x9cTape to Prevent Unwinding of Paper Web End of Paper Roll.xe2x80x9d This tab tb is formed of an adhesive tape 57, and a plurality of slits 58 are formed at equal intervals along the opposite side edges of the adhesive tape 57.
A plurality of tabs tb are affixed to the paper roll 52 such that the side edges thereof cross the end edge of the end portion 50 of the paper roll 52 substantially perpendicularly, thereby temporarily fixing the end portion 50 on the paper roll 52. When the paper web of a new paper roll 52 is to be joined to currently fed paper web, the pressure-sensitive double-sided adhesive tape 51 adhering to the end portion 50 of the new paper roll 52 is affixed to the currently fed paper web. As a result, each of the adhesive tapes 57 serving as the tabs ta is torn apart, along appropriate slits 58, into upper and lower pieces, so that the end portion 50 of the new paper roll 52 is released from temporary fixation.
FIGS. 10A and 10B show a tab tc disclosed in Japanese Utility Model Application Laid-Open (kokai) No. 5-12440 xe2x80x9cTab for Temporarily Fixing Paper Web End Portion of Paper Roll.xe2x80x9d In this tab tc, slits 60 are provided at a central portion between the upper and lower edges of a base sheet 59 and extend at appropriate intervals between the side edges thereof. An upper piece 61 is defined between the slits 60 and the upper edge of the base sheet 59, and a lower piece 62 is defined between the slits 60 and the lower edge of the base sheet 59. Adhesive layers 63 and 64 are provided on the back surfaces of the upper and lower pieces 61 and 62, respectively, in order to temporarily fix an end portion of a paper roll. Further, an adhesive layer 65 is provided on the front surface of the upper piece 61 in order to join paper webs.
The tab tc is mainly used for fixation of the vertex of an unillustrated chevron-shaped end portion of a paper roll. The adhesive layers 63 and 64 of the tab tc are affixed to the paper roll such that the slits 60 are aligned with the vertex of the chevron-shaped end portion of the paper roll, thereby temporarily fixing the chevron-shaped end portion on the paper roll. When the paper web of a new paper roll is to be joined to the currently fed paper web, the adhesive layer 65 is affixed to the currently fed paper web. As a result, the base sheet 59 is torn apart, along the slits 60, into the upper and lower pieces 61 and 62, so that the chevron-shaped end portion of the new paper roll is released from temporary fixation.
The tab ta disclosed in Japanese Utility Model Application Laid-Open (kokai) No. 4-117854 involves the following problem. When the paper roll 52 of FIG. 7xe2x80x94whose straight end portion 50 is temporarily fixed by an appropriate number of tabs ta of FIGS. 8A and 8B arranged at appropriate intervalsxe2x80x94is rotated acceleratedly and subjected to joining to the currently fed paper web by means of the pressure-sensitive double-sided adhesive tape 51, a tensile force is concentrated on the perforations 56 of all the tabs ta.
The perforations 56 of each tab ta subjected to the tensile force tend to be torn intermittently. Also, when the tensile force is exerted concurrently on all the tabs ta, the tabs ta tend to be torn intermittently. Accordingly, impact forces associated with the tearing of the individual tabs ta may not be exerted uniformly on the currently fed paper web with respect to its width direction; in other words, the impact forces may be exerted on the currently fed paper web in an unbalanced manner. As a result, the end portion 50 of the paper roll 52 and the currently fed paper wed adhering to the end portion 50 may both tear or deform, potentially failing to join together. Since the tabs ta adhering to the paper roll 52 are not torn smoothly as described above, use of the tabs ta involves poor reliability in joining paper webs.
In order to sequentially tear a plurality of tabs ta, a paper web end of the paper roll 52 may be cut obliquely with respect to the axis of the paper roll 52, and the tabs ta may be affixed to the oblique end portion of the paper roll 52. For example, as shown in FIG. 12, a plurality of tabs ta may be affixed to an oblique end portion 67 such that the perforations 56 thereof are substantially in parallel with the end portion 67, thereby temporarily fixing the end portion 67 on the paper roll 52. In this case, however, during the accelerated rotation of the paper roll 52, an air current arises around the rotating paper roll 52; thus, the resultant wind tends to enter beneath the nonadhesive portions 66 of the tabs ta. This causes entry of the wind beneath the end portion 67. As a result, the end portion 67 floats up in the air, and the tabs ta may be torn out before the joining of paper webs is completed, potentially resulting in unwinding of the paper roll 52.
In order to avoid the above-mentioned influence of an air current which arises around the rotating paper roll 52 during the accelerated rotation of the paper roll 52 and to sequentially tear a plurality of tabs ta adhering to the paper roll 52, as shown in FIG. 11, the tabs ta may be affixed to the oblique end portion 67 such that the perforations 56 thereof are in parallel with the axis of the paper roll 52. During the joining of paper webs, the oblique end portion 67 is affixed, successively from a leading edge toward a trailing edge with respect to the direction of rotation of the paper roll 52, to the currently fed paper wed. Thus, a tensile force is exerted on the tabs ta sequentially from the leading tab ta toward the trailing tab ta with respect to the direction of rotation of the paper roll 52, so that the tabs ta are torn sequentially.
However, since a difference substantially corresponding to the inclination angle of the end portion 67 exists between the direction of the tensile force acting along the inclined end portion 67 and the direction of the perforations 56 of the tab ta, the perforations 56 of the tab ta are torn forcedly, resulting in unsmooth tearing of the tab ta.
Thus, the tab ta is not suited for use in temporarily fixing an obliquely cut end portion of a paper roll.
The tab tb disclosed in Japanese Patent Application Laid-Open (kokai) No. 10-114452 involves the following problem. When the paper roll 52 of FIG. 7xe2x80x94whose end portion 50 is temporarily fixed by an appropriate number of tabs tb of FIGS. 9A and 9B arranged at appropriate intervalsxe2x80x94is rotated acceleratedly and subjected to joining to the currently fed paper web by means of the pressure-sensitive double-sided adhesive tape 51, a tensile force is concentrated on the slits 58 formed along the opposite side edges of the tapes 57 serving as the tabs tb.
However, the tab tb does not have a nonadhesive portion on the adhesive side thereof. Therefore, when the tab tb is torn, in addition to the strength of the material of the tab tb, the adhesion force resulting from adhesion of the tapes 57 to the underling paper surface acts against the tearing of the tab tb. Thus, even when the tensile force is exerted concurrently on the tabs tb, the tabs tb tend to be torn intermittently. Accordingly, impact forces associated with the tearing of the individual tabs tb may not be exerted uniformly on the currently fed paper web with respect to its width direction; in other words, the impact forces may be exerted on the currently fed paper web in an unbalanced manner. As a result, the end portion 50 of the paper roll 52 and the currently fed paper web adhering to the end portion 50 may tear or deform, potentially failing to join together. Since the tabs tb adhering to the paper roll 52 are not torn smoothly as described above, use of the tabs tb involves poor reliability in joining paper webs.
In order to sequentially tear a plurality of tabs tb, a paper web end of the paper roll 52 may be cut obliquely with respect to the axis of the paper roll 52, and the tabs tb may be affixed to the oblique web end portion of the paper roll 52 such that the upper and lower edges thereof (FIG. 9A) are substantially in parallel with the oblique web end portion, thereby temporarily fixing the oblique web end portion on the paper roll 52. In this case, however, the tab tb does not have a nonadhesive portion on the adhesive side thereof. Therefore, when the tab tb is torn, in addition to the strength of the material of the tab tb, the adhesion force resulting from adhesion of the tapes 57 to the underling paper surface acts against the tearing of the tab tb. Thus, a relatively large tensile force is required to tear the tabs tb adhering to the paper roll 52. As a result, the joining of paper webs may fail due to a failure to tear the tabs tb; therefore, the oblique end portion may not be reliably released from temporary fixation.
The tab tc disclosed in Japanese Utility Model Application Laid-Open (kokai) No. 5-12440 involves the following problem. When the tab tc of FIGS. 10A and 10B is torn into the upper piece 61 and the lower piece 62, the tearing force is exerted on the tab tc in a direction perpendicular to the slits 60. Accordingly, tears may develop from the opposite ends of the slit 60 in a direction intersecting with the slit 60 to reach the adhesive layers 63 and 65 of the upper piece 61. As a result, the upper piece 61 and the lower piece 62 may not be separated from each other; therefore, a web end portion of a paper roll may not be reliably released from temporary fixation.
An object of the present invention is to solve the above-mentioned problems involved in the conventional tabs and to provide a tab for fixing a paper web end portion of a paper roll, which tab can be attached to an obliquely cut end portion to be substantially perpendicular to the axial direction of the paper roll and substantially parallel to the end portion, so that the effective width of the tab is increased in order to securely fixed the end portion, thereby preventing unwinding of the end portion during accelerated rotation of the paper roll.
Another object of the present invention is to provide a tab for fixing a paper web end portion of a paper roll which permits smooth release of the paper web end portion from temporary fixation at the time of the joining of paper webs.
Still another object of the present invention is to provide a tab for fixing a paper web end portion of a paper roll which can be compactly arranged on a release sheet at short intervals so that the tabs arranged on the release sheet can be efficiently applied onto the paper roll by use of an automatic applicator.
To achieve the above objects, the present invention provides a tab for fixing a paper web end portion of a paper roll, comprising a substantially parallelogram-shaped base sheet having two diagonally opposite acute angles. A plurality of linear, discontinuous cuts are formed on the base sheet in parallel with two opposite sides of the base sheet to thereby define a first portion in cooperation with one of the two opposite sides and a second portion in cooperation with the other side. The cuts extend to at least one of other two opposite sides of the base sheet (the cut extending to the side of the base sheet is hereinafter referred to as an xe2x80x9copen cutxe2x80x9d). The tab further comprises adhesive layers applied to the first and second portions on the same surface such that an appropriate nonadhesive portion is formed between the adhesive layers and that a predetermined space is formed between the discontinuous cuts and each of said adhesive layers.
Through employment of the above parallelogram-shaped strip, the two sides of the tab in parallel with the cuts become longer than the width of the tab (the distance between the other two sides of the tab). Since the tab is affixed to a paper roll such that a line of cuts are aligned with the edge of the paper web end portion of the paper roll, an effective width of the tab becomes wider than the actual width of the tab. Thus, the paper web end portion of the paper roll is temporarily fixed in a reliable manner, so that the paper web end portion is not released from temporary fixation when the paper roll is rotated acceleratedly for the joining of paper webs.
The paper web end portion of the paper roll is affixed to the currently fed paper web and thus is released from temporary fixation, successively from a leading edge toward a trailing edge with respect to the direction of rotation of the paper roll. Since the tab is affixed to the paper roll in such an orientation that an open cut formed therein is located on the leading-edge side, tearing starts from the open cut and proceeds along a line of cuts.
Accordingly, even when the space between cuts is rendered relatively large in order to impart stiffness to the tab, the tab is readily torn along a line of cuts. Thus, the paper web end portion is smoothly released from temporary fixation.
Preferably, a release sheet having a size greater than that of the base sheet is attached to an adhesive-applied side of the base sheet such that a portion thereof is projected beyond the profile of the base sheet.
Employment of the above release sheet facilitates handling of the tab.
Preferably, the release sheet assumes the form of tape. The base sheets are arranged on the release sheet tape in the longitudinal direction of the tape. The release sheet tape is rolled up into a tab feed roll.
Employment of the above tab feed roll facilitates feed of the tabs.
Preferably, the base sheets are arranged on the release sheet tape in the longitudinal direction of the tape and such that the images of the adjacent base sheets projected in the width direction of the release sheet tape do not overlap each other. This feature facilitates application of the tabs performed by an automatic applicator, since the tab is released from the release sheet tape without interfering with the following tab. Further preferably, at least one of two acute corners of the base sheet is cut off. This feature enables the tabs to be arranged on the release sheet tape at shorter intervals, so that the release sheet tape of a predetermined length can carry a larger number of tabs. As a result, the automatic applicator is less frequently loaded with a tab feed roll, thereby improving the efficiency of the temporary-fixation work.